[Shadow Diver101]

Hi, I am very new to spearfishing and haven't even gone spearfishing yet. I am 15 and I'm not absolutely sure that I have the strength to pull back one of the rubber bands on a gun. My dad bought one that had 2 bands and I can barely pull those back. Is there a good technique to making it easier to pull back the bands or should I buy a pneumatic gun. Also please give me some recommendations on pneumatic guns under $300.